Sub-micron laser patterning of graphene and 2D materials

Abstract

An appropriately configured pulsed laser is focused onto a graphene sheet and is used to form a desired pattern in the graphene. When the laser pulse strikes the graphene, it modifies the bonding state of the carbon atoms in the graphene lattice, acting as a “blade” and causing a separation in the graphene sheet at the site of the laser pulse without causing damage to the surrounding graphene. The width of the separation, or “cut” in the graphene sheet can be controlled by controlling characteristics of the laser pulse such as beam shape, beam intensity, pulse width, repetition rate, and wavelength to produce a graphene material having desired electrical, optical, thermal, and/or mechanical properties.

What is claimed is: 
     
       1. A method for forming a laser-patterned two-dimensional material, comprising:
 focusing a pulsed laser beam on a two-dimensional material along a desired path; 
 wherein at least one of a wavelength, a beam shape, an optical fluence, a pulse width, and a pulse repetition rate of the pulsed laser beam is configured to cause the pulsed laser beam to ablate atoms from the two-dimensional material to form a channel in the two-dimensional material along the desired path without damaging the remainder of the two-dimensional material not illuminated by the pulsed laser beam; and 
 wherein the two-dimensional material is grown by chemical vapor deposition (CVD), a first layer of the two-dimensional material being patterned on a bottom surface thereof before the growth of a second layer of the two-dimensional material on a top surface of the first layer. 
 
     
     
       2. The method according to  claim 1 , wherein the two-dimensional material is graphene. 
     
     
       3. A method for forming a laser-patterned two-dimensional material, comprising:
 focusing a pulsed laser beam on a two-dimensional material along a desired path; 
 wherein at least one of a wavelength, a beam shape, an optical fluence, a pulse width, and a pulse repetition rate of the pulsed laser beam is configured to cause the pulsed laser beam to ablate atoms from the two-dimensional material to form a channel in the two-dimensional material along the desired path without damaging the remainder of the two-dimensional material not illuminated by the pulsed laser beam; and 
 wherein the two-dimensional material is molybdenum disulfide (MoS 2 ), molybdenum diselanide (MoSe 2 ), boron nitride (BN), tungsten disulfide (WS 2 ), or tungsten diselenide (WSe 2 ). 
 
     
     
       4. The method according to  claim 1 , wherein the pulsed laser beam is configured to produce a channel having a width less than about 1 μm in the two-dimensional material. 
     
     
       5. The method according to  claim 1 , wherein the two-dimensional material is patterned in situ while situated in a growth chamber, patterning being completed before the material is exposed to an ambient atmosphere. 
     
     
       6. A method for forming a laser-pattered two-dimensional material, comprising:
 focusing a pulsed laser beam on a two-dimensional material along a desired path; 
 wherein at least one of a wavelength, a beam shape, an optical fluence, a pulse width, and a pulse repetition rate of the pulsed laser beam is configured to cause the pulsed laser beam to ablate atoms from the two-dimensional material to form a channel in the two-dimensional material along the desired path without damaging the remainder of the two-dimensional material not illuminated by the pulsed laser beam; and 
 wherein the two-dimensional material is epitaxially grown, a first layer of the two-dimensional material being patterned on a top surface thereof before the growth of a second layer of the two-dimensional material on a bottom surface of the top layer. 
 
     
     
       7. A method for defining a desired current path for an electrical device formed on a two-dimensional material, comprising:
 focusing a pulsed laser beam on the two-dimensional material along a desired path; 
 wherein at least one of a wavelength, a beam shape, an optical fluence, a pulse width, and a pulse repetition rate of the pulsed laser beam is configured to cause the pulsed laser beam to ablate atoms from the two-dimensional material to form a plurality of channels around the electrical device without damaging the remainder of the two-dimensional material not illuminated by the pulsed laser beam; 
 wherein the two-dimensional material is grown by chemical vapor deposition (CVD), a first layer of the two-dimensional material being pattered on a bottom surface thereof before the growth of a second layer of the two-dimensional material on a top surface of the first layer; and 
 wherein the channels are configured to isolate the electrical device and to define a desired current path for the electrical device in the two-dimensional material. 
 
     
     
       8. The method according to  claim 7 , wherein the two-dimensional material is graphene. 
     
     
       9. A method for producing a two-dimensional material having desired electrical, optical, thermal, or mechanical properties, comprising:
 focusing a first pulsed laser beam on at least one predefined location on the two-dimensional material; 
 wherein at least one of a wavelength, a beam shape, an optical fluence, a pulse width, and a pulse repetition rate of the first pulsed laser beam is to cause the first pulsed laser beam to form one or more ablated channels having a desired extent of ablation in the two-dimensional material without damaging the remainder of the two-dimensional material not illuminated by the first pulsed laser beam, and 
 illuminating the two-dimensional material with a second pulsed laser beam, the second pulsed laser beam being configured to produce one or more unablated modified areas in the two-dimensional material without damaging the remainder of the two-dimensional material not illuminated by either the first or the second pulsed laser beam; and 
 wherein the extent of the ablation is tuned such that a combination of the ablated channels and the unablated modified areas produce the desired electrical, optical, thermal, or mechanical property of the two-dimensional material. 
 
     
     
       10. The method according to  claim 9 , wherein the two-dimensional material is graphene. 
     
     
       11. The method according to  claim 9 , wherein at least two channels having different extents of ablation are formed, the extent of ablation of the two-dimensional material in each channel being tuned to produce the desired electrical, optical, thermal, or mechanical property of the two-dimensional material. 
     
     
       12. A method for producing a two-dimensional material having desired electrical, optical, thermal, or mechanical properties, comprising,
 focusing a pulsed laser beam on at least one predefined location on the two-dimensional material; 
 wherein at least one of a wavelength, a beam shape, an optical fluence, a pulse width, and a pulse repetition rate of the pulsed laser beam is configured to cause the pulse laser beam to form one or more ablated channels having a desired extent of ablation in the two-dimensional material without damaging the remainder of the two-dimensional material not illuminated by the pulsed laser beam, the extent of ablation being tuned to produce a desired electrical, optical, thermal, or mechanical property of the two-dimensional material; 
 wherein the two-dimensional material is a multilayered two-dimensional material; and 
 wherein the pulsed laser beam is configured to pass through a first layer of the multilayered two-dimensional material to pattern a second layer of the multilayered two-dimensional material situated below the first layer. 
 
     
     
       13. A method for producing a multilayered two-dimensional material having a varying layer thickness, comprising:
 focusing a pulsed laser beam on a sheet of a first two-dimensional material along a desired path in the two-dimensional material, at least one of a wavelength, a beam shape, an optical fluence, a pulse width, and a pulse repetition rate being configured to cause the pulsed laser beam to ablate atoms from the first two-dimensional material and to form a channel in the first two-dimensional material in the portion of the first two-dimensional material illuminated by the laser beam without damaging a portion of the first two-dimensional material not illuminated by the pulsed laser beam to form a patterned first two-dimensional material; and 
 transferring a sheet of a second two-dimensional material onto the patterned first two-dimensional material to form a multi-layered two-dimensional material, wherein a portion of the multi-layered two-dimensional material comprising an unpatterned portion of the first two-dimensional material and the second two-dimensional material is two sheets thick and a portion of the multi-layered two-dimensional material comprising a patterned portion of the first two-dimensional material and the second two-dimensional material is one sheet thick. 
 
     
     
       14. A method for forming a laser-patterned two-dimensional material on a laser-sensitive substrate, comprising:
 focusing a pulsed laser beam on a two-dimensional material situated on a handle substrate and directing the pulsed laser beam along a desired path in the two-dimensional material, at least one of a wavelength, a beam shape, an optical fluence, a pulse width, and a pulse repetition rate being configured to cause the pulsed laser beam to ablate atoms from the two-dimensional material to produce a laser-patterned two-dimensional material having an ablated channel formed along the desired path, the ablated channel being formed without damaging the remainder of the two-dimensional material not illuminated by the pulsed laser beam; 
 removing the laser-patterned two-dimensional material from the handle wafer; and 
 transferring the laser-patterned two-dimensional material to the laser-sensitive substrate. 
 
     
     
       15. The method according to  claim 14 , wherein the laser-sensitive substrate is a flexible substrate formed from one of polyethylene tephthalate (PET), polyethylene naphthalate (PEN), and cellulose. 
     
     
       16. The method according to  claim 6 , wherein the two-dimensional material is graphene. 
     
     
       17. The method according to  claim 6 , wherein the pulsed laser beam is configured to produce a channel having a width less than about 1 μm in the two-dimensional material. 
     
     
       18. The method according to  claim 6 , wherein the two-dimensional material is patterned in situ while situated in a growth chamber, patterning being completed before the material is exposed to an ambient atmosphere. 
     
     
       19. The method according to  claim 12 , wherein the two-dimensional material is graphene. 
     
     
       20. The method according to  claim 12 , wherein at least two channels having different extents of ablation are formed, the extent of ablation of the two-dimensional material in each channel being tuned to produce the desired electrical, optical, thermal, or mechanical property of the two-dimensional material. 
     
     
       21. A method for defining a desired current path for an electrical device formed on a two-dimensional material, comprising:
 focusing a pulsed laser beam on a two-dimensional material along a desired path; 
 wherein at least one of a wavelength, a beam shape, an optical fluence, a pulse width, and a pulse repetition rate of the pulsed lasers beam is configured to cause the pulsed laser beam to ablate atoms from the two-dimensional material to form a plurality of channels around the electrical device without damaging the remainder of the two-dimensional material not illuminated by the pulsed laser beam; 
 wherein the two-dimensional material is epitaxially grown, a first layer of the two-dimensional material being patterned on a top surface thereof before the growth of a second layer of the two-dimensional material on a bottom surface of the top layer; and 
 wherein the channels are configured to isolate the electrical device and to define a desired current path for the electrical device in the two-dimensional material. 
 
     
     
       22. The method according to  claim 21 , wherein the two-dimensional material is graphene.